Regulating system



Feb. 22, 1938. E, HARDER 2,109,215

REGULATING SYSTEM Filed DGC. 24, 1935 2 ShGGtS-ShQGt 1 INVENTOR WITNESSES:

L. Harder.

Feb. 22, 1938. HARDER 2,109,215

REGULATING SYSTEM Filed Dec. 24, 1935 2 Sheets-Sheet 2 WITNESSES; INVENTOR Edwin L Harder. Q

Patented Feb. 22, 1938 PATENT OFFICE 2,109,218 aroma-ma srs'rm Edwin L. Harder,

Pittsburgh, Pa..- assignor' to eatinghonae. Electric a Manufacturing Com-- pany, East Pittsburgh, Pa, a corporation of Pennsylvania Application Deeember :4, lass. Serial m. 50.01:

iclaima.

My invention relates to electrical regulating systems, and it has particular relation to systems wherein a motor-operated rheostat is utilized to adjust the magnitude of the regulated quantity.

Generally stated, the object of my invention is to obtain finer steps of resistance adjustment than are afforded by a practical number of stationary rheostat contact buttons.

Another object is to lessen the wear on the 1 movable parts of the rheostat.

An additional object is to effect control within a narrow range by means supplemental to the equipment comprised by the conventional form of rheostatic regulator. 1

A further object is to supplement an automatic regulating system of the rheostatictype by a narrow-range vibrating-contact type of regulator.

In practicing my invention, I achieve the 20 above stated objects by providing the motoroperated quantity adjusting rheostat with control means which are sensitive only tions of predetermined magnitude in the regulated quantity. The rheostat is provided with a 25 special adjusting member which includes a pair of spaced contacting elements which are adapted at all times to span a portion of the rheostat resistor. A vibrating contact regulator sensitive to small variations in the regulated quantity is so then disposed to establish and interrupt at closely spaced time intervals and in adjustable ratio manner a shunt connection around the spanned portion of the resistor. This vibrating device thereby controls the regulated quantity within 85 a range which includes the predetermined larger variations to which the rheostat motor control means are responsive.

My invention, itself, together with additional objects and advantages thereof will best be 40 understood through the following description of a specific embodiment whentaken in conjunction with the accompanying drawings in which:

Figure 1 is a diagrammatic representation of apparatus and circuits comprised by one pre- 45 ferred form of the improved regulating system of my invention;

Fig. 2 is a representation of one preferred mechanical arrangement of the stationary contact buttons and the two spaced movable cooperating 50 elements comprised by the rheostat which iorms a part of the system of Fig. 1;

Fig. 3 is a diagrammatic representation of the basic form of system shown in Fig. 1 modified in that the rheostat operating motor derives con- 56 trol from the vibratory regulating element and to varia- 7 Fig. 4 is a partial reproduction of the sytem of Fig. 3 showing an alternate manner in which the form of control which it typifies may be carried out.

The system represented in Fig. 1 is adapted to maintain constant the voltage of an alternating current circuit II which is supplied from a polyphase generator or other dynamo-electric machine l2. The field winding ll of the generator is energized by an exciter it the field winding it of which in turn derives energizing current from any suitable source of direct current potential shown in the form of a pilot exciter 20.

For the purpose of adjusting the magnitude of this current to thereby control the voltage of generator [2, a rheostat 22 is connected in the manner shown in the energizing circuit of the exciter field winding. Operation of this rheostat is effected in well known manner-by a motor 24 which is controlled through a pair of relays 28 and 28 by means of a contact making device 30. The actuating winding 32 of this device is energized through a transformer 34 by a measure of the voltage of regulated circuit Hi.

When, for example, this voltage falls by a pre determined amount below the desired value, device ll completes through contact members 36 and R an actuating circuit which causes relay 2' to so eflect energization of motor 24 that it operates the rheostat 22 in a direction which lowers its effective resistance to thereby correctively raise the voltage of generator l2. Similarly, a rise in the voltage by a predetermined magnitude above the desired value results in the engagement of contact members 36 and L to effect an adjustment of rheostat 22 in the opposite or generator-voltage-lowering direction.

In the conventional type of rheostatic regulator, the contact making device ill is made sufficiently sensitive to correct for most objectionable variations in the regulated quantity. This frequently requires more or less continuous operation of the rheostat 22, and results in an objectionable amount of wear to relatively heavy moving parts which are expensive to replace. Furthermore, rheostats having a so-called practical number of stationary contact buttons are frequently incapable of providing resistance adjustment steps of the fineness desirable in many applications and for this reason may be incapable of maintaining the regulated quantity within limits as close as the application calls for. The expedient of my invention now to he described eifectively overcomes the above objectionable featurcs.

In achieving the desired objects I provide the movable member 40 of the rheostat 22 with a pair of elements A and B which are spaced in the manner shown to span a portion 42 of the rheostat resistor. In Fig. 2 one mechanical arrangement of the plurality of stationarily mounted contact buttons 44 which in a conventional device are connected with individual sections. of the rheostat resistor is more completely illustrated.

The spanned resistor section 42 is arranged to be periodically shunted by one or more relays 40 to thereby vary the eifective resistance thereof. The opening and closing action of these relays is controlled by a vibrating-contact regulating device 48 which is sensitive to small variations in the voltage of regulated circuit ll.

As shown in Fig.1, the regulator 48 comprises a main control winding 5| energized by the same measure of the regulated circuit voltage as is the beforedescribed motor control device 30. This winding exerts an upwardly acting pull upon a plunger II which is linked to one end of a bar it suspended at its center from the lower end of a bell-crank lever 58 and carrying at its opposite end a counter-balancing weight 60. Suspended from the horizontal portion of bellcrank it by means of a spring 62 is a vibrating element assemblage which includes a plunger 64 upon which a winding 54 exerts an upwardly acting force.

The bar 58 carries a contact member 06 which is disposed to engage a cooperating stationary member 88 in order to complete an energizing circuit for a master relay 10. This relay controls the actuation of resistor shunting relays 48 and also that of a vibration-forcing relay 12, which is disposed, upon actuation, to short circuit a resistor 14 and thereby lower the impedance of the energizing circuit for vibrating element winding 54.

The described vibrating-contact regulator functions to adjust the excitation supplied to the regulated machine by periodically short circuiting the section 42 of rheostat resistance in the excitation control circuit. When contacts 66-48 are closed all the time, the current supplied is maximum and when open all the time a minmum value of current is obtained. By varying the ratio of time that the regulator contacts are closed to the time that they are opened, any value of average current betweenthe limits determined by the section of resistance 42 can be obtained.

In operation of this regulator, engagement of contact members 6648 effects actuation of master relay 10, which in turn causes actuation of relay 12 to short circuit resistor 14, thereby raising the voltage impressed upon the vibrating control winding 54. The resulting increase in upward pull exerted on plunger 64 allows a tension spring ii to rotate the bell-crank 59 in a counter-clockwise direction, thereby moving contact 66 to the right and out of engagement with member 88.

This interruption effects the opening of both relays I0 and 12, thereby lowering the voltage impressed upon winding 54 to its original value. The decrease in upward pull on the associated plunger member rotates bell-crank 59 in a clockwise direction thereby moving contact member 66 to the left to reestablish its engagement with member 88. As a consequence, the contact members are again caused to separate in the manner just described and a continuous vibration thereof is eiIected at a frequency of the order of several times per second.

The elevational position of the horizontally oscillating contact member 68 is determined by the magnitude of the voltage of circuit II, a measure of which acts upon the main control winding SI of the regulator. Changes in voltage thus act to vary the ratio of the time that the contacts are closed to the time that they are open. By moving member 66 to a lower position, a decrease in the generator voltage increases the value of this ratio, while by raising the member an increase in generator voltage decreases the ratio value.

Resistor shunting relays 48 follow the vibrating movement of master relay I0 and thereby periodically open and close a shunt circuit around resistor section 42. When the voltage of circuit it drops, these relays increase the ratio of the time that the resistor section 42 is short circuited to the time that it is active in the excitation supply circuit with the result that the excitation supplied to machine I2 is appropriately increased to correctively raise the machine voltage back to the desired value.

In a similar manner a rise in the regulated voltage acts to lower the ratio of time that the resistor section 42 is short-circuited to the time that it is active in the excitation-determining circuit with the result that the excitation supplied to machine I2 is lowered and the output voltage thereof correctively lowered back to the desired value.

In this manner the vibrating regulator 40 serves to control the regulated voltage within a range determined by the magnitude of the spanned portion 42 of the rheostat resistor. In practice, this span is so chosen that it will include the predetermined variations from the desired value to which the rheostat motor controlling device 30 is sensitive. For the purpose of effecting this adjustment, the contacting elements A and B may, as shown in Fig. 2, be mounted upon a supporting member of insulating material 8i in a manner to permit of their,

sensitive the control device 30 is made, the less.

frequently will adjustments of rheostat 22 by motor 24 be required and the broader must be the range of control efiected by the vibrating regulator 48.

In some situations it may be preferable 0 allow the vibratory regulator 48 to control not only the effective resistance 01' rheostat section 42, but the operation of rheostat adjusting motor 24 as well. One manner of doing this is shown in Fig. 3. There the motor control relay II is energized by the same pulsatory voltage, from source 80, that is impressed upon the vibratory relays 46 and 12.

In the arrangement shown this voltage is impressed upon the main winding 32 of the control relay through a circuit which includes a pulsation-smoothing reactor 82. The relay is also provided with a flux-lag winding 84 short-circuited upon itself as shown. The combined eflect is to cause the relay to respond to the ratio of timeopen to time-closed periods of the vibrating contacts 6648.

When this ratio is high, indicating that the effective resistance of rheostat section 42 approaches the maximum and that the assemblage gage member L to thereby eflect the above described rheostat adjustment. When, on the other hand, this ratio is low, contact member 36 of the relay is brought into engagement with member R and adjustment oi the rheostat in the opposite direction takes place.

In consequence, whenever the vibratory regulator 48 approaches either limit of its range of control, the rheostat 22 is automatically adjusted to correctively recentralize the section I! which is spanned by the movable contacts A and B of the rheostat.

A modiflcation'in this basic is shown in Fig. 4. There the relay device II is replaced by a pair of relays O0 and '8. Relay It is of the under-voltage responsive type and is connected to actuate the "raise contactor 28 for the rheostat operating motor 24 whenever the time-open to time-closed ratio of regulator contacts 60-" approaches its high or maximum limit.

Relay 8., on the other hand, is of the overvoltage responsive type which picks up when the above ratio approaches its minimum. value and in so doing actuates the lower contactcr 2! for the rheostat motor. .The energizing circuit oi! this relay is shown as including a currentsmoothing reactor 02 and a rectifier 9| connected in a local circuit therewith for the purpose of making the relay 8! more sensitive to the vibratory regulator action.

Although I have shown and described a certain specific embodiment of my invention, I am fully aware that many modifications thereof are possible. My invention therefore is not to be restricted except insofar as is necessitated by the prior art and by the scope of the appended claims.

I claim as my invention:

1.- In a regulating system wherein a tapped-resistor type of rheostat operated by a motor controlled by means sensitive to variations in a characteristic 01' an electrical circuit is utilized to adjust said characteristic, the combination oi a resistance-adjusting member for said rheostat which comprises a pair of spaced contacting elements adapted to span diflerent portions 0! like resistance value of the rheostat resistor, and a vibrating-contact regulator, separate from the rheostat .motor control means and sensitive to said characteristic, disposed to establish and interrupt at closely spaced time intervals and in adjustable-ratio manner a shunt connection around the resistor portion between the spaced contacting elements to thereby control the circuit a characteristic within a range determined by the spanned portion oi! said rheostat resistor.

2. A regulating system comprising a quantityadiusting rheostat which includes a resistor, an operating motor therefor, motorcontrol means sensitive to variations of predetermined magnitude in the regulated quantity, a resistance-ad- Justing member for said rheostat comprising a pair of spaced contacting elements adapted to span diiierent portions of like resistance value of the rheostat resistor, and a vibrating-contact regulator, separate from the rheostat motor control means and sensitive to variations in said quantity which are smaller than those designated above, disposed to establish and interrupt at closely spaced time intervals and in adjustableratio manner a shunt connection around the resistor portion between the spaced contacting elemethod of controlments to thereby control the regulated quantity within a narrow range.

3. A regulating system comprising a quantityadjusting rheostat which includes a resistor, an operating motor therefor, motor-control means sensitive to variations of predetermined magnitude in the regulated quantity, 9. resistance-adjusting member for said rheostat comprising a pair of spaced contacting elements adapted to span diiierent portions of like resistance value 0! the rheostat resistor, and a vibrating-contact regulator, separate from said motor-control means and sensitive to variations in said quantity which are smaller than those designated above. disposed to establish and interrupt at closely spaced time intervals and in adjustable-ratio manner ashunt connection around the resistor portion included between the spaced contacting elements to thereby control the regulated quantity within a narrow range, the magnitude of the resistor portion spanned by said spaced contacts being so chosen that the range of quantity control eiiected by the vibrating-contact regulator includes the predetermined variations first reierred to.

4. A regulating system comprising a quantityadjusting rheostat which includes a resistor, a resistance-adjusting member for said rheostat comprising a pair of spaced movable contacting elements adapted to span like portions of said resistor, a vibrating contact regulator, sensitive to variations in the regulated quantity, disposed to establish and interrupt at closely spaced time intervals and in adjustable-ratio manner a shunt connection around the portion of said resistor included between said spaced contacting elements, a motor for changing the position of said rheostat adjusting member, and motorcontrol means sensitive to the ratio of the timeopen to time-closed periods of the vibratory regulator contacts for adjusting the position of said contacting elements.

5. Ina regulator system, a circuit to be regulated, means for controlling an electrical quantity of said circuit comprising a resistor, a pair of spaced contact members simultaneously movable to vary the eflective value of said resistor and arranged in spaced relation to include similar portions of said resistor therebetween, regulator means responsive to the regulated quantity for varying to positions of said spaced contact member, and separate regulator means also responsive to the regulated quantity for varying the effective value of the resistor portion included between said pair of spaced movable contact members.

6. In a regulator system, a circuit to be regulated, means for controliingan electrical quantity of said circuit comprising a resistor, a pair of spaced contact members simultaneously movable to vary the efiective value of said resistor and arranged in spaced relation to include similar portions of said resistor therebetween, motor operated regulator means responsive to the regulated quantity for varying to positions of said spaced, contact member, and regulator means operable independently of said first-named regulator means responsive to the regulated quantity for varying the effective value oi! the resistor portion included between said pair of spaced movable contact members, said second-named regulator means being sensitive to relatively small changes in the regulated quantity and said first-named regulator means being responsive to relatively large changes in the regulated trolling a regulated quantity of said machine and comprising a resistor and a pair of spaced movable contact members for engaging said resistor to include like portions of the resistor therebetw een independently oi the positions thereof, a regulator sensitive to the regulated quantity for varying the effective value of the portion of the resistor included between saidspaced contact members, and means actuated upon the approach of said regulator to the end of itsrange of operation for operating said spaced contact members in the one or the other direction to increase the range of regulation controlled by said regulator in the corresponding direction.

8. In a regulator system, in combination. a dynamo-electric machine, a rheostat for controlling a regulated quantity of said machine comprising a resistor and a pair of spaced movable contact members i'or connecting said resistor to include like portions of the resistor therebetween independently of the positions thereof, a vibratory regulator sensitive to the regulated quantity for varying the efiective value of the portion of the resistor included between said spaced contact members, and motor operated means also responsive to the regulated quantity and operable independently of said regulator means for varying the range or control governed by said regulator means in the one or the other direction.

9. In a regulator system, in combination, a dynamo-electric machine, a rheostat for controlling a regulated quantity of said machine comprising a resistor and a pair of spaced movable contact members for connecting said resistor to include like portions of the resistor therebetween independently of the positions thereof, a vibratory regulator sensitive to the regulated quantity for varying the effective value of the portion of the resistor included between said spaced contact members, and motor operated means controlled by said vibratory regulator and operative upon the approach of said vibratory regulator to the end 01' its range of operation for operating said movable contact members in a direction to increase the range of regulation by said vibratory regulator in the one or the other direction.

EDWIN L. HARDER. 

